Energy control elements for improved microwave heating of packaged articles

ABSTRACT

Processes and systems that enhance the heating of packaged foodstuffs and other items in various microwave heating systems are described herein. The foodstuffs may be contained in a package including one or more energy control elements that interact with microwave energy in order to alter the effect that microwave energy has on the foodstuff. These energy control elements can enhance or inhibit microwave energy and a single package may include one or more energy control elements. In some cases, the energy control element may respond differently to different types of microwave energy. As a result, some packages described herein may exhibit different absorption or reflectance characteristics when exposed to microwave energy while being pasteurized or sterilized in a larger-scale microwave heating system than when the package is reheated in an at-home microwave oven prior to consumption or use.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/921,327, filed on Mar. 14, 2018, which claims priority to U.S.Provisional Patent Application No. 62/471,654, filed on Mar. 15, 2017,the entire disclosures of which are expressly incorporated by referenceherein in their entirety.

FIELD OF THE INVENTION

The present invention relates processes and systems for heating articlesusing microwave energy. In particular, the present invention relates tomethods and systems for providing enhanced heating to packaged materialsthat are pasteurized or sterilized in large-scale microwave heatingsystems, including those which are then reheated in a consumer microwaveoven prior to consumption or use.

BACKGROUND

Commercially-available packaged food items are often pasteurized orsterilized prior to being purchased by a consumer. Many of these itemsare also designed to be reheated by the consumer in an at-home microwaveoven prior to consumption. However, because of the differences inconditions during the pasteurization or sterilization of the packagedfoodstuff and its reheating, the foodstuff may develop “hot” and “cold”spots that are difficult or impossible to control simply withadjustments to the process and/or equipment. In some cases, for example,the hot and cold spots may occur because of spatial constraints (e.g.,the orientation of the package within the heating chamber), or becauseof a physical property of the foodstuff (e.g., its dielectric constant).

Thus, a need exists for a package suitable for use in bothcommercial-scale pasteurization or sterilization and at-home consumermicrowave ovens that facilitates uniform heating of packaged foodstuffsand other packaged items under a variety of conditions.

SUMMARY

One embodiment of the present invention concerns a process for heating aplurality of articles in a microwave heating system, the processcomprising: (a) loading a group of the articles into a carrier, whereineach of the articles includes a package at least partially filled withat least one foodstuff, wherein at least a portion of the foodstuff inone or more of the packages is positioned near at least one energycontrol element; (b) passing the loaded carrier through a microwaveheating chamber in a direction of travel along a first convey line; (c)generating microwave energy; (d) during at least a portion of thepassing, discharging at least a portion of the microwave energy into themicrowave heating chamber; and (e) heating the articles using at least aportion of the microwave energy discharged into the microwave heatingchamber. During the heating, the portion of the foodstuff positionednear the energy control element is heated to a substantially differenttemperature and/or at a substantially different heating rate than theportion of the foodstuff would have been heated to or at if the energycontrol element was not present.

Another embodiment of the present invention concerns a process forheating a plurality of articles in a microwave heating system, theprocess comprising: (a) loading a carrier with a plurality of thearticles, wherein each article comprises a package at least partiallyfilled with at least one item to be heated; (b) passing the loadedcarrier through a microwave heating chamber in a direction of travelalong a convey line; (c) during at least a portion of said passing,directing microwave energy into the microwave heating chamber via one ormore microwave launchers; and (d) during at least a portion of thedirecting, heating the articles with at least a portion of the microwaveenergy in order to increase the temperature of the coldest portion ofeach item to a target temperature. At least a portion of the packagesinclude at least one microwave inhibiting element for inhibiting orpreventing microwave energy from reaching at least a portion of the itemduring the heating.

Yet another embodiment of the present invention concerns an articlesuitable for being pasteurized or sterilized in a microwave heatingsystem, the article comprising at least one foodstuff; and a packagecomprising at least one compartment for holding the foodstuff. Thepackage further comprises at least one energy control element foraltering the interaction between at least a portion of the foodstuff andmicrowave energy when the package is exposed to microwave energy. Theenergy control element is configured to exhibit at least one of thefollowing characteristics (i) and (ii)-(i) absorb polarized andnon-polarized or randomly polarized microwave energy differently; and(ii) reflect polarized and non-polarized or randomly polarized microwaveenergy differently.

Still another embodiment of the present invention concerns a process forheating a packaged foodstuff using microwave energy, the processcomprising: (a) at least partially filling a package with at least onefoodstuff to form a packaged foodstuff, wherein the package includes atleast one energy control element; (b) heating the packaged foodstuffusing a first type of microwave energy to thereby sterilize orpasteurize the foodstuff, wherein the heating is performed in acommercial-scale microwave heating system and includes passing a carrierloaded with the packaged foodstuff along a convey line; and (c)reheating the article with a second type of microwave energy to therebyprovide a ready-to-eat foodstuff. The first and second types ofmicrowave energy have substantially different (i) polarizations, (ii)frequencies, and/or (iii) intensities and wherein the energy controlelement is substantially more effective at inhibiting or enhancing oneof the first and second types of microwave energy than the other.

A further embodiment of the present invention concerns a process fordesigning a package for the sterilization and/or pasteurization of afoodstuff, wherein the process comprises: (a) filling an initial packagewith a test material to provide a test article; (b) heating the testarticle in a first microwave heating system using polarized microwaveenergy; (c) during at least a portion of the heating of step (b),measuring the temperature of the test material at one or more locationswithin the test article; (d) determining the location of at least onehot spot or cold spot based on the temperatures measured in step (c);(e) creating a modified package, wherein the creating includes one ormore of the actions (i) through (iv)-(i) adding a microwave inhibitingelement near a hot spot; (ii) adding a microwave enhancing element neara cold spot; (iii) removing a microwave inhibiting element from near acold spot; and (iv) removing a microwave enhancing element from near ahot spot; (f) filling the modified package with the test material toprovide a modified test article; and (g) heating the modified testarticle in the microwave heating system.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention are described in detailbelow with reference to the attached drawing Figures, wherein:

FIG. 1a is a side view of a pouch suitable for use in holding foodstuffsand other items according to embodiments of the present invention,particularly illustrating the width of the top and bottom portion of thepouch and its height;

FIG. 1b is an isometric view of the pouch shown in FIG. 1 a;

FIG. 2a is an isometric view of a tray suitable for use in holdingfoodstuffs and other items according to embodiments of the presentinvention, particularly showing the length, width, and height dimensionsof the tray;

FIG. 2b is a top view of the tray shown in FIG. 2 a;

FIG. 2c is a side view of the tray shown in FIGS. 2a and 2 b;

FIG. 2d is an end view of the tray shown in FIGS. 2a -2 c;

FIG. 3 is a partial isometric view of a tray according to embodiments ofthe present invention including a plurality of energy control elements;

FIG. 4 is an isometric end view of the tray shown in FIG. 3,particularly illustrating the configuration of the energy control stripswith the tray shown in phantom;

FIG. 5 is a top front isometric view of a carrier suitable for use inone or more embodiments of the present invention;

FIG. 6 is a bottom front isometric view of the carrier shown in FIG. 5;

FIG. 7 is an end view of the carrier shown in FIGS. 5 and 6;

FIG. 8 is a side view of the carrier shown in FIGS. 5-7;

FIG. 9 is a longitudinal cross-sectional view of the carrier shown inFIGS. 5-8;

FIG. 10 is a transverse cross-sectional view of the carrier shown inFIGS. 5-9;

FIG. 11 is a side view of a plurality of articles arranged in a nestedconfiguration;

FIG. 12 is a is a top view of a plurality of articles arranged in anested configuration, particularly illustrating a divided row nestedconfiguration;

FIG. 13 is a top view of another plurality of articles arranged in anested configuration, particularly illustrating a full or continuousnested configuration;

FIG. 14a is a schematic depiction of the major steps of a method formicrowave pasteurizing or sterilizing a packaged foodstuff according toembodiments of the present invention;

FIG. 14b is a schematic depiction of the major zones of a system formicrowave pasteurizing or sterilizing a packaged foodstuff according toembodiments of the present invention;

FIG. 15 is a schematic partial side cut-away view of a microwave heatingzone configured according to embodiments of the present invention,particularly illustrating one possible arrangement of the microwaveheating vessel, the microwave launchers, and the microwave distributionsystem;

FIG. 16 is an isometric view of a microwave launcher configuredaccording to embodiments of the present invention;

FIG. 17 is a longitudinal side view of the microwave launcher depictedin FIG. 16;

FIG. 18a is an end view of the microwave launcher generally depicted inFIGS. 16 and 17, particularly illustrating a launcher having a flaredoutlet;

FIG. 18b is an end view of another embodiment of the microwave launchergenerally depicted in FIGS. 16 and 17, particularly illustrating alauncher having an inlet and outlet of approximately the same size;

FIG. 18c is an end view of yet another embodiment of the microwavelaunchers generally depicted in FIGS. 16 and 17, particularlyillustrating a launcher having a tapered outlet; and

FIG. 19 is a schematic diagram of the major steps of a process fordesigning a package for the sterilization or pasteurization of afoodstuff according to embodiments of the present invention.

DETAILED DESCRIPTION

The present invention relates to methods, systems, and packages forpasteurizing and sterilizing a foodstuff or other item in a larger-scalemicrowave heating system that may also be reheated in a consumermicrowave oven to provide a satisfactory ready-to-eat foodstuff.Examples of microwave heating systems used for pasteurization orsterilization include any suitable liquid-filled, continuous microwaveheating system including, for example, those similar to the microwaveheating systems described in U.S. Patent Application Publication No.US2013/0240516, which is incorporated herein by reference in itsentirety. Additionally, although described herein generally withreference to a foodstuff, it should be understood that embodiments ofthe present invention also relate to the pasteurization or sterilizationof other types of items such as medical and dental instruments ormedical and pharmaceutical fluids, which may or may not need to bereheated by the consumer prior to use.

When a packaged food item is pasteurized or sterilized in a microwaveheating system and is then subsequently reheated in a consumer microwaveoven, the foodstuff may be exposed to different types and/or amounts ofmicrowave energy. Additionally, in some cases, the package may includetwo or more different types of food items, at least one of which mayneed less exposure to microwave energy than one or more of the others.This requirement for less microwave exposure may exist because, forexample, the foods have different dielectric properties and/or differentheating requirements (e.g., target time and/or temperature) to achievethe desired level of pasteurization or sterilization.

When a food item having lower heating requirements such as, for example,requiring less microwave exposure, is also highly susceptible to heatdegradation, packaging that item with another food item having higherheating requirements may not be possible with conventional packaging.This is because the lower heating requirement food item may experiencetoo much degradation during the sterilization process or the higherheating requirement food item. In some cases, this discrepancy may beaddressed by enhancing or reducing the microwave heating of certainareas of the foodstuff during the sterilization or pasteurizationprocess. However, this same enhancement or reduction of microwaveheating may or may not be desirable during microwave reheating by theconsumer.

According to some embodiments of the present invention, packages thatinclude at least one energy control element for adjusting how microwaveenergy interacts with at least a portion of a packaged item areprovided. As used herein, the term “energy control element” refers toany element or device that interacts with microwave energy in order toalter the effect that microwave energy has on the item being heated.Energy control elements have not been used for adjusting microwaveenergy in a pasteurization or sterilization system, which typicallyutilizes a different type of microwave energy and field than themicrowave energy utilized by an at-home microwave. Thus, conventionalshielding panels and other devices used exclusively in at-home microwaveovens do not perform the same way in the microwave heating systems usedfor pasteurization or sterilization described herein.

Energy control elements may be used to enhance or reduce heating inproblematic package areas. For example, in some cases, an energy controlelement may be located near an easily-sterilized food item to reduceheating and prevent overheating, while, in other cases, an energycontrol element may be used to enhance microwave heating near a packagedfood having high heating requirements. Thus, strategically-locatedenergy control elements are useful for reducing, or even eliminating,hot and/or cold spots in a single food package. Energy control elementsmay also be used in multi-food packages and, in particular, inmulti-food packages that include two food items having differentdielectric properties and/or for packages in which one or more fooditems require less heating than the another. Additionally, such energycontrol elements may be particularly useful when the food item requiringless heating is also more susceptible to thermal degradation.

In some cases, the energy control element may comprise a selectiveenergy control element configured to enhance or reduce microwave heatingin a certain way or to a certain degree in one heating environment(e.g., a microwave pasteurization or sterilization system) and mayenhance and/or reduce microwave heating in a different way or to adifferent degree in another heating environment (e.g., reheating inat-home microwave oven). For example, in some cases, two different fooditems in a single package may need to receive similar amounts ofmicrowave heating during pasteurization or sterilization to ensureadequate microbial lethality rates, but it may be desirable for one ofthe items to be reheated more than the other in a consumer microwaveoven (e.g., apple sauce and lasagna). In other cases, two differentitems in a single package may need to receive different amounts ofenergy during pasteurization or sterilization to prevent degradation ofthe food requiring less heat for sterilization. However, duringreheating, it may be desirable to provide both foods with the same levelof heating to ensure proper end temperature (e.g., lasagna and greenbeans).

The selectivity of an energy control element may depend on one or moreproperties of the microwave energy used to heat the item. For example,the selectivity of the energy control element may depend on thefrequency, polarity, or intensity of the microwave energy being used toheat the packaged item. Selective energy control elements may besubstantially more effective at inhibiting or enhancing one type ofmicrowave energy than another and, as a result, may perform differentlywhen exposed to each type

For example, a selective energy control element may be substantiallymore effective at inhibiting or enhancing a first type of microwaveenergy that has a different frequency than another type of microwaveenergy. For example, a selective energy control element may besubstantially more effective at inhibiting or enhancing microwave energyhaving a frequency of not more than 1200 MHz than microwave energyhaving a frequency of at least 2200 MHz. Alternatively, a selectiveenergy control element may be substantially more effective at inhibitingor enhancing microwave energy having a frequency of at least 2200 MHzthan microwave energy having a frequency of not more than 1200 MHz. Insome cases, a selective energy control element may be configured toinhibit or enhance at least about 1, at least about 2, at least about 5,at least about 10, at least about 15, at least about 20, at least about25, at least about 30, at least about 35, at least about 40, at leastabout 45, at least about 50, at least about 55, or at least about 60percent more of microwave energy of one frequency than another.

Examples of different frequencies of microwave energy include microwaveenergy having a frequency of at least about 700 MHz, at least about 750MHz, at least about 800 MHz, at least about 850 MHz, or at least about900 MHz and/or not more than about 1200 MHz, not more than about 1150MHz, not more than about 1100 MHz, not more than about 1050 MHz, notmore than about 1000 MHz, or not more than about 950 MHz and microwaveenergy having a frequency of at least about 2200 MHz, at least about2250 MHz, at least about 2300 MHz, at least about 2350 MHz, or at leastabout 2400 MHz and/or not more than about 2600 MHz, not more than about2550 MHz, not more than about 2500 MHz, or not more than about 2475 MHz.Typically, microwave pasteurization and sterilization systems may employmicrowave energy having a frequency of about 915 MHz (e.g., not 2450MHz), while at-home (consumer) microwave ovens usually utilize microwaveenergy having a frequency of about 2450 MHz (e.g., not 915 MHz).

In some cases, a selective energy control element may be substantiallymore effective at inhibiting or enhancing a first type of microwaveenergy that has a different polarization than another type of microwaveenergy. For example, a selective energy control element may besubstantially more effective at inhibiting or enhancing polarizedmicrowave energy than non-polarized or randomly polarized microwaveenergy. Alternatively, a selective energy control element may besubstantially more effective at inhibiting or enhancing non-polarized orrandomly polarized microwave energy than polarized microwave energy.Typically, microwave pasteurization and sterilization systems employpolarized microwave energy, while at-home ovens utilize non-polarized orrandomly polarized microwave energy. In some cases, a selective energycontrol element may be configured to inhibit or enhance at least about10, at least about 15, at least about 20, at least about 25, at leastabout 30, at least about 35, at least about 40, at least about 45, atleast about 50, at least about 55, or at least about 60 percent more ofone of polarized and non-polarized or randomly polarized microwaveenergy than the other.

The selective energy control element may be substantially more effectiveat inhibiting or enhancing microwave energy with a substantially higherintensity, or it may be more effective at inhibiting or enhancingmicrowave energy at a lower intensity. Additionally, in some cases, theselective energy control element may inhibit or enhance one type ofmicrowave energy while being substantially transparent to another. Asused herein, the term “transparent” as it refers to microwave energymeans that the material or element permits at least 97 percent of theincident microwave energy to pass therethrough without inhibiting orenhancing the interaction between the microwave energy and the foodstuffor other item. In some cases, a transparent material or element canpermit at least about 98, at least about 98.5, at least about 99, or atleast about 99.5 percent of the incident microwave energy to passtherethrough without inhibiting or enhancing the interaction between themicrowave energy and the foodstuff or other item. When an energy controlelement is transparent to a type of microwave energy, it performs thesame as if such an energy control element were absent.

It has been found that selective use of one or more energy controlelements positioned near a foodstuff may be used to control the heatingrate at which and/or temperature to which the foodstuff is being heated.As a result, the presence of hot and cold spots can be adjusted andeasily-heated or easily-pasteurized or sterilized foodstuffs may becontained in a single package with foodstuffs that are not as easilyreheated or pasteurized or sterilized. For example, in some cases,positioning an energy control element near a foodstuff or other itembeing heated, can cause the foodstuff or other item being heated to havea substantially different heating rate and/or a substantially differenttemperature than the foodstuff or other item would have been heated toor at if the energy control element was not present, under identicalconditions. As used herein, the term “different” refers to values thatare higher or lower than a given value. Thus, a “different” temperaturemay be higher or lower than a given temperature.

In some cases, the foodstuff or other item positioned near an energycontrol element may have heating rate that is at least about 1, at leastabout 2, at least about 5, at least about 10, at least about 12, atleast about 15, at least about 18, at least about 20, at least about 22,at least about 25, at least about 28, or at least about 30° C./mindifferent than the heating rate of the item if the energy controlelement was not present. Alternatively, or in addition, the foodstuffnear the energy control element can have a heating rate that is not morethan about 500, not more than about 400, not more than about 200, notmore than about 100, not more than about 50, not more than about 25, ornot more than about 10° C./min different than the heating rate if theenergy control element was not present. In some cases, the heating rateof the foodstuff near the energy control element can be at least about2, at least about 5, at least about 10, at least about 15, at leastabout 20, at least about 25, at least about 30, at least about 35, atleast about 40, at least about 45, at least about 50, at least about 55,or at least about 60 percent different (i.e., higher or lower) than theheating rate of the foodstuff if the energy control element was notpresent.

In some cases, the foodstuff or other item positioned near the energycontrol element may have a different temperature than if the energycontrol element was not present. For example, the difference intemperature may be at least about 1, at least about 2, at least about 5,at least about 8, at least about 10, at least about 12, or at leastabout 15° C. and/or it can be not more than about 40, not more thanabout 35, not more than about 30, not more than about 25, not more thanabout 22, not more than about 20, not more than about 18, not more thanabout 15, not more than about 12, or not more than about 10° C. In somecases, the temperature of the foodstuff near the energy control elementcan be at least about 5, at least about 10, at least about 15, at leastabout 20, at least about 25, at least about 30, at least about 35, atleast about 40, at least about 45, at least about 50, at least about 55,or at least about 60 percent different (i.e., higher or lower) than ifthe energy control element was not present.

Different types of energy control elements may be used, depending onwhether the microwave heating is to be enhanced or reduced. When theenergy control element is configured to enhance microwave heating, it isreferred to as an “microwave enhancing element.” A susceptor is one typeof microwave enhancing element. The microwave enhancing element may beconfigured to absorb at least about 5, at least about 10, at least about15, at least about 20, at least about 25, or at least about 30 percentof the incident microwave energy that contacts it. As used herein, theterm “incident microwave energy” refers to the microwave energy incidenton the particular energy control element and is not necessarily equal tothe total amount of microwave energy introduced into the heatingchamber. Microwave enhancing elements absorb microwave energy andincrease the temperature and/or heating rate of the materials positionednear the element.

In some cases, the microwave enhancing element may be configured toabsorb at least about 5, at least about 10, at least about 15, at leastabout 20, at least about 25, at least about 30, at least about 35, atleast about 40, at least about 45, at least about 50, at least about 55,at least about 60, at least about 65, at least about 70, at least about75, at least about 80, at least about 85, at least about 90, at leastabout 95 percent of the total amount of incident microwave energy.Alternatively, or in addition, it may absorb not more than about 95, notmore than about 90, not more than about 85, not more than about 80, notmore than about 75, not more than about 70, not more than about 65, notmore than about 60, not more than about 55, not more than about 50, notmore than about 45, not more than about 40, not more than about 35, notmore than about 30, not more than about 25, not more than about 20, notmore than about 15, not more than about 10, or not more than about 5percent of the total amount of incident microwave energy.

The foodstuff or other item positioned near a microwave enhancingelement may be heated to a higher temperature and/or at a faster heatingrate than the foodstuff or other item would be heated to or at if themicrowave enhancing element was not present. For example, the portion ofthe foodstuff positioned near the microwave enhancing element mayachieve a temperature of at least about 65, at least about 70, at leastabout 75, at least about 80, at least about 85, at least about 90, atleast about 95, at least about 100, at least about 105, at least about110, at least about 115, at least about 117, at least about 120, or atleast about 121, at least about 125° C., whereas the food may only havebeen heated to a temperature of not more than about 120, not more thanabout 115, not more than about 110, not more than about 105, not morethan about 100, not more than about 95, not more than about 90, not morethan about 85, not more than about 80, not more than about 75, not morethan about 70, not more than about 65, or not more than about 60° C. inthe absence of the microwave enhancing element. When heated to a highertemperature, the foodstuff positioned near the microwave enhancingelement may also be heated at a faster heating rate than if thesusceptor were absent, or the heating rate may be slower or the same.

Additionally, or in the alternative, when a microwave enhancing elementis used, the portion of the foodstuff or other article positioned nearthe microwave enhancing element may be heated at a faster heating ratethan if the microwave enhancing element were absent. For example, whenpositioned near a microwave enhancing element, the foodstuff may have aheating rate of at least about 10, at least about 15, at least about 20,at least about 25, at least about 30, at least about 35, at least about40, at least about 45, at least about 50, at least about 55, at leastabout 60, at least about 65, at least about 70, or at least about 75°C./min, while the foodstuff may have a heating rate of not more thanabout 50, not more than about 45, not more than about 40, not more thanabout 35, not more than about 30, or not more than about 25° C./min, ifthe microwave enhancing element were absent. When heated at a fasterrate, the foodstuff positioned near the microwave enhancing element mayachieve a temperature higher than, lower than, or similar to thefoodstuff if the microwave enhancing element were absent.

When the energy control element is configured to inhibit microwaveenergy, it is referred to as an “microwave inhibiting element.” Somemicrowave inhibiting elements are reflectors. In some embodiments, amicrowave inhibiting element may be configured to reflect at least about5, at least about 10, at least about 15, at least about 20, at leastabout 25, or at least about 30 percent of the incident microwave energythat contacts it. Microwave inhibiting elements reduce or, in somecases, nearly eliminate, microwave energy contacting some portion of thefoodstuff or other item. As a result, the foodstuff may be heated to alower temperature and/or at a lower heating rate than if the microwaveinhibiting element were absent. In some cases, the microwave inhibitingelement may reflect at least about 5, at least about 10, at least about15, at least about 20, at least about 25, at least about 30, at leastabout 35, at least about 40, at least about 45, at least about 50, atleast about 55, at least about 60, at least about 65, at least about 70,at least about 75, at least about 80, at least about 85, at least about90, at least about 95 percent of the total incident microwave energy.Alternatively, or in addition, it may reflect not more than about 95,not more than about 90, not more than about 85, not more than about 80,not more than about 75, not more than about 70, not more than about 65,not more than about 60, not more than about 55, not more than about 50,not more than about 45, not more than about 40, not more than about 35,not more than about 30, not more than about 25, not more than about 20,not more than about 15, not more than about 10, or not more than about 5percent of the total amount of incident microwave energy.

When a microwave inhibiting element is used, the foodstuff positionednear the microwave inhibiting element may receive less than the totalamount of microwave energy directed toward it. As a result, it may beheated to a lower temperature and/or at a slower heating rate than ifthe microwave inhibiting element was not present. For example, thefoodstuff positioned near the microwave inhibiting element may have aheating rate of not more than about 100, not more than about 75, notmore than about 50 not more than about 40, not more than about 35, notmore than about 30, not more than about 25, not more than about 20, ornot more than about 15° C./min, while the foodstuff may only have aheating rate of at least about 15, at least about 20, at least about 25,at least about 30, at least about 35, at least about 40, at least about50, at least about 75, at least about 100, at least about 150, or atleast about 200° C./min, if the microwave inhibiting element was notpresent. When the portion of the foodstuff or other item positioned nearthe microwave inhibiting element is heated at a slower rate, it mayachieve approximately the same temperature as, or a differenttemperature than, the foodstuff or other item would achieve if themicrowave inhibiting element were not present.

Additionally, or in the alternative, the foodstuff positioned near themicrowave inhibiting element may be heated to a lower temperature thanit would be heated if the microwave inhibiting element were not present.For example, the foodstuff near the microwave inhibiting element may beheated to a temperature of not more than about 125, not more than about123, not more than about 122, not more than about 121, not more thanabout 120, not more than about 115, not more than about 110, not morethan about 105, not more than about 100, not more than about 95, notmore than about 90, not more than about 85, not more than about 80, notmore than about 75, not more than about 70, or not more than about 65°C. If no microwave inhibiting element were present, the foodstuff may beheated, under identical conditions, to a temperature of at least about65, at least about 70, at least about 75, at least about 80, at leastabout 85, at least about 90, at least about 95, at least about 100, atleast about 105, at least about 110, at least about 120, at least about121, at least about 122, at least about 125° C. The foodstuff may beheated at the same or a different heating rate than if the microwaveinhibiting element was not present.

In some embodiments, the energy control element, whether a microwaveinhibiting element, a microwave enhancing element, or both, may beincorporated into the package. When the energy control element is partof the package, it may be incorporated into the package itself, or maybe temporarily positioned on or around at least a portion, or all, ofthe package (e.g., as a sleeve or wrap). When the energy control elementis an integral part of the package in which the foodstuff or other itembeing heated is held, it may be present on at least a portion, or all,of the top, bottom, and/or sides of the package. In some cases, one ormore of these areas of the package may simply be formed of a materialthat acts as an energy control element, while the remaining portions ofthe package are formed from another, typically microwave transparentmaterial including, but not limited to, plastics, cellulosics, andcombinations thereof.

The package itself may be of any suitable form. For example, in somecases, the packages used may include pouches. The pouches may beindividual, detached pouches that are not connected to any otherpouches. The pouches can be flexible, semi-flexible, or rigid. Eachpouch can include one internal compartment for holding a foodstuff orother item, or it may include two or more separate compartments. Oneexample of a pouch is shown in FIGS. 1a and 1 b.

As shown in FIGS. 1a and 1b , each pouch 150 has a top portion 152 and abase portion 154 that is wider than top portion 152. The base portion154 of the pouch 150 can be at least twice, at least three times, or atleast four times wider than the top portion 152. Alternatively, the baseportion 154 and the top portion 152 have approximately the same width.The width of the top portion 152, shown as W₁ in FIG. 1a , can be atleast about 0.01, at least about 0.05, or at least about 0.10 inchesand/or not more than about 0.25, not more than about 0.20, or not morethan about 0.15 inches, or it can be in the range of from about 0.01 toabout 0.25 inches, about 0.05 to about 0.20 inches, or from about 0.10to about 0.15 inches. Alternatively, the width of the top portion 152may be at least about 0.5, at least about 0.75, at least about 1, atleast about 1.5 and/or not more than about 3, not more than about 2.5,not more than about 2, not more than about 1.5, or not more than about 1inch, or it can be in the range of from about 0.5 to about 3 inches,about 0.75 to about 2.5 inches, about 1 to about 2 inches, or about 1 toabout 1.5 inches.

The width of the base portion 154, shown as W₂ in FIG. 1a , can be atleast about 0.5, at least about 0.75, at least about 1, at least about1.5 and/or not more than about 3, not more than about 2.5, not more thanabout 2, not more than about 1.5, or not more than about 1 inch, or itcan be in the range of from about 0.5 to about 3 inches, about 0.75 toabout 2.5 inches, about 1 to about 2 inches, or about 1 to about 1.5inches. The height of the pouch 150, shown as H in FIG. 1b , can be atleast about 2, at least about 3, at least about 4, or at least about 4.5inches and/or not more than about 12, not more than about 10, or notmore than about 8 inches, or it can be in the range of from about 2 toabout 12 inches, about 3 to about 10 inches, about 4 to about 8 inches.Pouches of other dimensions may also be suitable in various cases.

In other embodiments, the packages used may include trays. Traysgenerally have a top and a bottom and a general prism-like shape. Trayscan have a square, rectangular, or elliptical cross-section, althoughother shapes may be suitable. One example of a tray 250 is illustratedin FIGS. 2a-d . Each tray may have a single compartment for holding thefoodstuff or other item to be heated, as shown in FIGS. 2a-d , or it mayinclude two or more compartments at least partially isolated from oneanother (not shown).

In some cases, tray 250 may have a top that is longer and wider than itsbottom so that it has a generally trapezoidal shape, as generally shownin FIGS. 2a-d . As used herein, the terms “length” and “width” refer tothe longest and second longest, respectively, non-diagonal dimensions ofa package. When the tray has a trapezoidal shape such that the top islonger and wider than the bottom, the length and width are measured atthe largest cross-section (usually the top surface). The height is theshortest non-diagonal dimension measured perpendicular to the planesdefined by the length and width. The length (L), width (W), and height(h) of tray 250 are shown in FIGS. 2a -d.

The length (L) of each tray can be at least about 1, at least about 2,at least about 4, or at least about 6 inches and/or not more than about18, not more than about 12, not more than about 10, not more than about8, or not more than about 6 inches, or it can be in the range of fromabout 1 to about 18 inches, about 2 to about 12 inches, about 4 to about10 inches, or about 6 to about 8 inches. The width (W) of each tray maybe at least about 1 inch, at least about 2 inches, at least about 4inches, at least about 4.5 inches, or at least 5 inches and/or not morethan about 12 inches, not more than about 10 inches, not more than about8 inches, or not more than 6 inches, or it can be in the range of fromabout 1 inch to about 12 inches, about 2 inches to about 10 inches,about 4 inches to about 8 inches, about 4.5 inches to about 6 inches, orabout 5 inches to about 6 inches. Each tray may have a height (h) of atleast about 0.5 inches, at least about 1 inch, at least about 1.5 inchesand/or not more than about 8 inches, not more than about 6 inches, ornot more than about 3 inches, or it can be in the range of from about0.5 to about 8 inches, about 2 to about 6 inches, or 1.5 to 3 inches.Trays of other dimensions may also be suitable, depending on theparticular application.

When the energy control element is part of the package, whether a pouch,a tray, or other container, it may cover all or a portion of the totalsurface area of the package. For example, the energy control element maycover at least about 5, at least about 10, at least about 15, at leastabout 20, at least about 25, at least about 30, at least about 35, atleast about 40, at least about 45, at least about 50, at least about 55,at least about 60, at least about 65, at least about 70, at least about75, at least about 80, at least about 85, at least about 90, or at leastabout 95 percent of the total surface are of the package. In some cases,it may cover the entire surface area of the package.

Additionally, or in the alternative, the energy control element maycover not more than about 95, not more than about 90, not more thanabout 85, not more than about 80, not more than about 75, not more thanabout 70, not more than about 65, not more than about 60, not more thanabout 55, not more than about 50, not more than about 45, not more thanabout 40, not more than about 35, not more than about 30, not more thanabout 25, not more than about 20, not more than about 15, not more thanabout 10, or not more than about 5 percent of the total surface area ofthe package.

Energy control elements can be in any suitable shape. In some cases, theenergy control elements in the form of strips that are printed, labeled,laminated, or otherwise incorporated into all or a portion of thepackage. In some embodiments, these types of energy control elements maybe microwave enhancing elements and can be formed from a metallicmaterial. Such energy control elements may be incorporated into or ontoall or a portion of the package surface by printing, by lamination, orby application of labels that include the strips. In some cases,lamination may be used with flexible packages, while labels and printingmay be used for rigid packaging. When the package includes a tray and alid, the energy control strips may be present on the lid, on the tray,or on both the tray and the lid. An example of a tray 252 including aplurality of energy control strips 260 is shown in FIGS. 3 and 4.

Although only covering one portion of the tray 252 in the embodimentshown in FIGS. 3 and 4, it should be understood that the energy controlstrips 260 may cover more or less of the surface area of the tray 252,or may be positioned at different locations. Alternatively, or inaddition, one or more of the energy control elements may be in adifferent shape, and/or the package may be a pouch or other type ofcontainer.

When the energy control elements are present as strips, the package mayinclude at least 2, at least 3, at least 4, at least 5, at least 6, atleast 7, at least 8, at least 9, at least 10, at least 11, or at least12 or more strips that are spaced apart from one another along at leastone surface of the package. Each of the strips may have a width, orsecond longest dimension, of at least about 1/64, at least about 1/32,or at least about 1/16 of an inch and/or not more than about ½, not morethan about ¼, or not more than about ⅛ of an inch. The size of eachstrip may be the same as the others, or one or more may have a differentwidth. The strips may be spaced such that there are at least 2, at least3, at least 4, at least 5, or at least 6 strips and/or not more than 15,not more than 14, not more than 12, or not more than 10 strips per thepredominant wavelength of microwave energy to which the package isexposed during at least one heating step. In some cases, the predominantwavelength of which microwave energy to which the package can be exposedduring at least one heating step is at least about 1.4, at least about1.5, at least about 1.6, or at least about 1.65 inches and/or not morethan about 2, not more than about 1.9, not more than about 1.8, or notmore than about 1.75 inches.

In some cases, the spacing between adjacent strips may be as wide as, orwider than, the width of each strip. Further, the spacing between setsof adjacent strips may be the same or different. In some cases, thewidth of the open area between adjacent energy control strips can be atleast about 10, at least about 15, at least about 20, at least about 25,at least about 30, at least about 35, at least about 40, at least about45, or at least about 50 percent wider than the average width of the twoadjacent energy control strips. Alternatively, or in addition, the widthof the open area between adjacent energy control strips can be not morethan about 90, not more than about 85, not more than about 80, not morethan about 75, not more than about 70, not more than about 65, or notmore than about 60 percent wider than the average width of the twoadjacent energy control strips.

The packaged foodstuff may be configured such that one or morefoodstuffs in the package are positioned near the energy controlelement. For example, the energy control element may be positioned suchthat at least about 5, at least about 10, at least about 15, at leastabout 20, at least about 25, at least about 30, at least about 35, atleast about 40, at least about 45, at least about 50, at least about 55,at least about 60, at least about 65, at least about 70, at least about75, at least about 80, at least about 85, at least about 90, at leastabout 95, or up to 100 percent of at least one foodstuff is positionednear the energy control element.

Alternatively, part of the foodstuff (or another foodstuff) may not bepositioned near the energy control element. For example, at least about5, at least about 10, at least about 15, at least about 20, at leastabout 25, at least about 30, at least about 35, at least about 40, atleast about 45, at least about 50, at least about 55, at least about 60,at least about 65, or at least about 75 percent of the foodstuff in apackage may not be positioned near the energy control element. This mayoccur when, for example, the package includes two or more differentfoodstuffs in a single or multi-compartment tray or pouch.Alternatively, the package may include two or more energy controlelements (of the same or a different type) each positioned neardifferent types of foodstuff. In this way, the temperature and heatingprofile of different foodstuffs within a single package can beeffectively controlled to achieve more efficient and uniform heating ofthe foodstuff or other item within the package.

In some cases, the energy control element may be part of a carrier usedto secure and transport the articles through a microwave heating system.Carriers may be used in larger-scale microwave heating systemsconfigured for the pasteurization or sterilization of packagedfoodstuffs and other items. Several views of an exemplary carrier areprovided in FIGS. 5-10. As particularly shown in FIGS. 5 and 6, thecarrier 10 includes an outer frame 12, an upper support structure 14,and a lower support structure (not shown). The outer frame 12 comprisestwo spaced-apart side members 18 a,b and two spaced-apart end members 20a,b. The first and second end members 20 a,b may be coupled to andextend between opposite ends of first and second side members 18 a,b toform outer frame 12. When each of side members 18 a,b are longer thanthe end members 20 a,b, the frame may have a generally rectangularshape, as shown FIGS. 5 and 6.

As shown in FIGS. 5, 6, 7, and 10, first and second side members 18 a,beach include respective support projections 22 a,b that are configuredto engage respective first and second convey line support members, whichare represented by dashed lines 24 a and 24 b in FIG. 8. The first andsecond support projections 22 a,b of carrier 10 present first and secondlower support surfaces 42 a,b for supporting carrier 10 on first andsecond convey line support members 24 a,b. Convey line support members24 a,b may be a moving convey line element such as, for example, a pairof chains (not shown) located on each side of carrier 10 as it movesthrough the microwave heating zone in a direction represented by thearrow in FIG. 8.

The first and second side members 18 a,b and first and second endmembers 20 a,b may be formed of any suitable material including, forexample, a low loss material having a loss tangent of not more thanabout 10′, not more than about 10⁻³, or not more than about 10⁻²,measured at 20° C. Each of the side members 18 a,b and end members 20a,b may be formed of the same material, at least one may be formed of adifferent material. Examples of suitable low loss tangent materials mayinclude, but are not limited to, various polymers and ceramics. In someembodiments, the low loss tangent material may be a food-grade material.

When the low loss material is a polymeric material, it may have a glasstransition temperature of at least about 80° C., at least about 100° C.,at least about 120° C., at least about 140° C., or at least about 160°C., at least about 165° C., in order to withstand the elevatedtemperatures to which the carrier may be exposed during heating of thearticles. Suitable low loss polymers can include, for example,polytetrafluoroethylene (PTFE), polysulfone, polynorbornene,polycarbonate (PC), acrylonitrile butadiene styrene (ABS), poly(methylmethacrylate) (PMMA), polyetherimide (PEI), polystyrene, polyvinylalcohol (PVA), polyvinyl chloride (PVC), and combinations thereof. Thepolymer can be monolithic or it may be reinforced with glass fibers,such as, for example glass-filed PTFE (“TEFLON”). Ceramics, such asaluminosilicates, may also be used as the low loss material.

As shown in FIGS. 5 and 6, the carrier 10 may include an upper supportstructure 14 and a lower support structure 16 for holding a group ofarticles within the carrier, while also permitting microwave energy passthrough the carrier 10 to the articles. In the example shown in FIGS. 5and 6, the upper and lower support structures 14, 16 may each include aplurality of support members extending between the end members 20 a,b ina direction substantially parallel to the side members 18 a,b. Thesupport members may extend in a direction substantially perpendicular tothe end members 20 a,b. As used herein, the terms “substantiallyparallel” and “substantially perpendicular” mean within 5° of beingparallel or perpendicular, respectively. In other instances (not shown),upper and lower support structures 14, 16 could include a grid member orsubstantially rigid sheets of a microwave transparent orsemi-transparent material extending between the side members 18 a,b andend members 20 a,b. Additional details regarding the number, dimensions,and configurations of support structures 14 and 16 are provided in U.S.patent application Ser. No. 15/284,173, the entirety of which isincorporated herein by reference.

When the upper and/or lower support structures 14, 16 include individualsupport members as shown in FIGS. 5 and 6, one or more of the supportmembers may be formed of a strong, electrically conductive material.Suitable electrically conductive materials can have a conductivity of atleast about 10³ Siemens per meter (S/m), at least about 10⁴ S/m, atleast about 10⁵ S/m, at least about 10⁶ S/m, or at least about 10⁷ S/mat 20° C., measured according to ASTM E1004 (09). Additionally, theelectrically conductive material may have a tensile strength of at leastabout 50 MegaPascals (MPa), at least about 100 MPa, at least about 200MPa, at least about 400 MPa, or at least about 600 MPa, measuredaccording to ASTM E8/E8M-16a, and/or it may also have a yield strengthof at least about 50, at least about 100, at least about 200, at leastabout 300, or at least about 400 MPa at 20° C., measured according toASTM E8/E8M-16a. The Young's Modulus of the electrically conductivematerial can be at least about 25 GigaPascals (GPa), at least about 50GPa, at least about 100 GPa, or at least about 150 GPa and/or not morethan about 1000 GPa, not more than about 750 GPa, not more than about500 GPa, or not more than about 250 GPa, measured at 20° C., measuredaccording to ASTM E111-04 (2010). The electrically conductive materialmay be metallic and, in some cases, may be a metal alloy. The metalalloy may include any mixture of suitable metal elements including, butnot limited to, iron, nickel, and/or chromium. The electricallyconductive material may comprise stainless steel and may be food-gradestainless steel.

As particularly shown in FIGS. 7-10, carrier 10 defines a cargo volume32 for receiving and holding a plurality of articles 40. Cargo volume 32is at least partially defined between the upper and lower supportstructures 14 and 16, which are vertically spaced apart from oneanother, and the side 18 a,b and end 20 a,b members. The articlesreceived in cargo volume 32 may be in contact with and/or held inposition by at least a portion of the individual support members presentin the upper and lower support structures 14 and 16. Each of upper andlower support structures 14, 16 may be coupled to outer frame 12 in aremovable or hinged manner so that at least one of the upper and lowersupport structures 14, 16 may be opened to load the articles 40 intocarrier 10, closed to hold the articles 40 during heating, and openedagain to unload the articles 40 from the carrier. In some embodiments,as shown in FIG. 10, the use of one or more longitudinal dividers 34 maycreate multiple compartments 36 a-d within cargo volume 32 for receivingmultiple rows of articles 40.

Cargo volume 32 can be of any suitable size. In some cases, it can havea length measured between opposing internal surfaces of the first andsecond end members 20 a,b, in the range of from about 0.5 to about 10feet, about 1 to about 8 feet, or about 2 to about 6 feet. The cargovolume 32 may also have a width measured between opposing internalsurfaces of the first and second side members 18 a,b, in the range offrom about 0.5 to about 10 feet, about 1 to about 8 feet, or from about2 to about 6 feet. The height of the cargo volume, which can be measuredbetween opposing internal surfaces of the upper and lower supportstructures 14, 16, can be in the range of from about 0.50 to about 8,from about 0.75 to about 6, from about 1 to about 4, or from about 1.25to about 2 inches. Overall, the cargo volume can have a total volume inthe range of from about 2 to about 30 cubic feet, about 4 to about 20cubic feet, about 6 to about 15 cubic feet, or about 6.5 to about 10cubic feet.

Additionally, in some embodiments, the carrier may further include atleast one article spacing member 34 for adjusting the size and/or shapeof the cargo volume 32. Examples of article spacing members includedividers 34, as shown in FIGS. 5, 6, and 10, for dividing the cargovolume 32 into two or more compartments and vertical spacers, such as 38a,b shown in FIG. 9, for adjusting the vertical height between the upperand lower support structures 14, 16. When present, the article spacingmember or members 34 may be permanently or removably coupled to theouter frame 12 or at least one of the upper and lower support structures14, 16. When an article spacing member, such as a divider 34 or avertical spacer 38, is removably coupled to the outer frame 12 and/or tothe upper and lower support members 14, 16, it may be selectivelyinserted into and removed from the carrier 10 in order to change thesize and/or shape of the cargo volume 32 so that the carrier 10 may holdmany types of articles having different sizes and/or shapes. Furtherdetails regarding such carriers are provided in the '173 Application.

When loaded into a carrier as described herein, the articles are placedwithin the cargo volume 32 defined between the upper and lower supportstructures of the carrier. As discussed above, the cargo volume may be asingle volume, or it may be divided into two or more compartments, suchas 36 a-d shown in FIG. 10, using one or more dividers 34. When loadedinto the cargo volume 32, the articles may be placed in single rowsalong the length of the carrier. In some embodiments, the articles maybe arranged in at least 2, at least 3, at least 4, at least 5, or atleast 6 single rows and/or not more than 15, not more than 12, not morethan 10, or not more than 8 single rows, or from 2 to 15 single rows,from 3 to 12 single rows, from 4 to 10 single rows, or from 5 to 8single rows. Overall, each carrier may hold a total of at least 6, atleast 8, at least 10, at least 12, at least 16, at least 18, at least20, at least 24, at least 30 articles and/or not more than 100, not morethan 80, not more than 60, not more than 50, or not more than 40articles, or it can hold from 6 to 100 articles, from 8 to 80 articles,from 10 to 60 articles, from 12 to 50 articles, or from 18 to 40articles. Articles can be loaded into the carrier in any suitablemanner, including manually or using an automated device.

When loaded into a carrier, each of the articles loaded into the cargovolume may be similar, or two or more articles may be different from oneanother. In some cases, the articles loaded into a carrier may include afirst group of a first type of article and a second group of a secondtype of article, with the first type of article and second type ofarticle having different packages and/or different types of contentswithin the packages. The articles may be spaced apart from one anotherwithin the carrier, or one or more articles may contact at least aportion of one or more other articles. It may be desirable, in somecases, to minimize spacing between the articles so that the averagedistance between consecutive edges of adjacent articles loaded in thecarrier can be not more than about 1 inch, not more than about 0.75inches, not more than about 0.5 inches, not more than about 0.25 inches,or not more than about 0.1 inch. There may be no gaps between thearticles such that adjacent articles are in contact with one anotherwhen loaded into the carrier, or at least a portion of adjacent articlesmay overlap horizontally.

The particular arrangement of the articles within the cargo space maydepend, at least in part, on the shape of the articles. For example,when the articles have a general trapezoidal-like shape, such that thearticles are longer and wider on the top than on the bottom, thearticles may be arranged in a nested configuration. FIG. 11 provides aside view of one row of articles 40 a-f arranged in a nestedconfiguration.

In the nested configuration, adjacent articles have oppositeorientations. In the nested configuration, the articles 40 a-f loadedinto the carrier are sequentially oriented in the direction of travel,indicated by the arrow 50 in FIG. 11, in a top down, top up, top down,top up configuration. As shown in FIG. 11, the bottom of the secondarticle 40 b is oriented between the top of the first article 40 a andthe top of the third article 40 c. Additionally, in the nestedconfiguration, the tops of one set of alternating articles 40 b, d, fand the bottoms of the other set of alternating articles 40 a, c, econtact the upper support structure, while the bottoms and tops of eachset of alternating articles contact the lower support structure whenarticles are loaded into the carrier.

Two top views of a plurality of articles arranged in different nestedconfigurations in a carrier are provided in FIGS. 12 and 13. In each ofFIGS. 12 and 13, the tops of articles are marked with a “T,” the bottomsarticles are marked with a “B,” and the direction of travel of thecarrier is shown by the arrow 50. In the example shown in FIG. 12, thearticles are arranged in several spaced-apart rows that are eacharranged in a nested configuration, and FIG. 13 shows a fully nestedarticle pattern, wherein the individual rows of nested articles are notspaced from one another and the articles are arranged in a nestedconfiguration in both the longitudinal and transverse directions.

As discussed previously, articles as described herein may be heated in amicrowave heating system used to pasteurize and/or sterilize thearticles. In general, pasteurization involves the rapid heating of amaterial to a minimum temperature between 80° C. and 100° C., whilesterilization involves heating the material to a minimum temperaturebetween about 100° C. and about 140° C. Some of the microwave systemsdescribed herein may be used for pasteurization or for sterilization. Insome cases, pasteurization and sterilization may take placesimultaneously, or nearly simultaneously, so that the articles beingprocessed are both pasteurized and sterilized by the heating system.

Turning now to FIGS. 14a and 14b , schematic diagrams of the main stepsof a microwave heating process and the main elements of a microwaveheating system suitable for pasteurizing and/or sterilizing articlesaccording to embodiments of the present invention are provided. As usedherein, the term “microwave energy” generally refers to electromagneticenergy having a frequency between 300 MHz and 30 GHz.

As shown in FIGS. 14a and 14b , the articles loaded into one or morecarriers can initially be introduced into a thermalization zone 112,wherein the articles can be thermalized to a substantially uniformtemperature. Once thermalized, the articles can optionally be passedthrough a pressure adjustment zone 114 a before being introduced into amicrowave heating zone 116. In microwave heating zone 116, the articlescan be rapidly heated using microwave energy discharged into at least aportion of the heating zone by one or more microwave launchers, asgenerally shown as launchers 124 in FIG. 14b . The heated articles canthen be passed through a holding zone 120, wherein the coldest portionof each article can be maintained at a temperature at or above apredetermined target temperature (e.g., a pasteurization orsterilization target temperature) for a specified amount of time. Thearticles can also be passed to a quench zone 122, wherein thetemperature of the articles can be quickly reduced to a suitablehandling temperature. Thereafter, the cooled articles can optionally bepassed through a second pressure adjustment zone 114 b before beingremoved from the system.

The above-described thermalization, microwave heating, holding, and/orquench zones of the microwave system depicted in FIGS. 14a and 14b canbe defined within a single vessel, or at least one of theabove-described stages or zones can be defined within one or moreseparate vessels. Additionally, in some cases, at least one of theabove-described steps can be carried out in a vessel that is at leastpartially filled with a liquid medium in which the articles beingprocessed can be at least partially submerged. As used herein, the term“at least partially filled” denotes a configuration where at least 50percent of the volume of the specified vessel is filled with a liquidmedium. In certain embodiments, the volume of at least one of thevessels used in the thermalization zone, the microwave heating zone, theholding zone, and the quench zone can be at least about 75 percent, atleast about 90 percent, at least about 95 percent, or 100 percent filledwith a liquid medium.

The liquid medium used may be any suitable liquid medium. For example,the liquid medium may have a dielectric constant greater than thedielectric constant of air and, in one embodiment, can have a dielectricconstant similar to the dielectric constant of the articles beingprocessed. Water (or a liquid medium comprising water) may beparticularly suitable for systems used to heat consumable articles. Theliquid medium may also include one or more additives, such as, forexample, oils, alcohols, glycols, and salts in order to alter or enhanceits physical properties (e.g., boiling point) at the conditions ofoperation.

The microwave heating systems as described herein may include at leastone conveyance system (not shown in FIGS. 14a and 14b ) for transportingthe articles through one or more of the processing zones describedabove. Examples of suitable conveyance systems can include, but are notlimited to, plastic or rubber belt conveyors, chain conveyors, rollerconveyors, flexible or multi-flexing conveyors, wire mesh conveyors,bucket conveyors, pneumatic conveyors, screw conveyors, trough orvibrating conveyors, and combinations thereof. Any suitable number ofindividual convey lines can be used with the conveyance system, and theconvey line or lines may be arranged in any suitable manner within thevessels.

In operation, the loaded carriers introduced into the microwave systemdepicted in FIGS. 14a and 14b are initially introduced into athermalization zone 112, wherein the articles are thermalized to achievea substantially uniform temperature. For example, at least about 85percent, at least about 90 percent, at least about 95 percent, at leastabout 97 percent, or at least about 99 percent of all the articleswithdrawn from the thermalization zone 112 have a temperature withinabout 5° C., within about 2° C., or within 1° C. of one another. As usedherein, the terms “thermalize” and “thermalization” generally refer to astep of temperature equilibration or equalization.

When the thermalization zone 112 is at least partially filled with aliquid medium, the articles in the carrier passing through thethermalization zone 112 can be at least partially submerged in theliquid during the passing. The liquid medium in the thermalization zone112 can be warmer or cooler than the temperature of the articles passingtherethrough and, in some cases, can have an average bulk temperature ofat least about 30° C., at least about 35° C., at least about 40° C., atleast about 45° C., at least about 50° C., at least about 55° C., or atleast about 60° C. and/or not more than about 100° C., not more thanabout 95° C., not more than about 90° C., not more than about 85° C.,not more than about 80° C., not more than about 75° C., not more thanabout 70° C., not more than about 65° C., or not more than about 60° C.

The thermalization step can be carried out under ambient pressure or itmay be carried out in a pressurized vessel. When pressurized,thermalization may be performed at a pressure of at least about 1, atleast about 2, at least about 5, or at least about 10 psig and/or notmore than about 80, not more than about 50, not more than about 40, ornot more than about 25 psig. When the thermalization zone 112 is liquidfilled and pressurized, the pressure may be in addition to any headpressure exerted by the liquid. Articles undergoing thermalization canhave an average residence time in the thermalization zone 112 of atleast about 30 seconds, at least about 1 minute, at least about 2minutes, at least about 4 minutes and/or not more than about 20 minutes,not more than about 15 minutes, or not more than about 10 minutes. Thearticles withdrawn from the thermalization zone 112 can have an averagetemperature of at least about 20° C., at least about 25° C., at leastabout 30° C., at least about 35° C. and/or not more than about 70° C.,not more than about 65° C., not more than about 60° C., or not more thanabout 55° C.

When the thermalization zone 112 and microwave heating zone 116 mayoperate at substantially different pressures, the carrier withdrawn fromthe thermalization zone may be passed through a pressure adjustment zone114 a before entering the microwave heating zone. When used, thepressure adjustment zone 114 a may be any zone or system configured totransition the carrier between an area of lower pressure and an area ofhigher pressure. The difference between the low and high pressure zonesmay vary depending on the system and can, for example, be at least about1 psig, at least about 5 psig, at least about 10 psig, at least about 12psig and/or not more than about 50 psig, not more than about 45 psig,not more than about 40 psig, or not more than about 35 psig. When thequench zone 122 shown in FIGS. 14a and 14b is operated at a differentpressure than the microwave heating zone 116, another pressureadjustment zone 114 b may be present to transition the carrier betweenthe microwave heating zone 116 or hold zone 120 and quench zone 122. Insome cases, the first pressure adjustment zone 114 a can transition thecarrier from a lower pressure thermalization zone to a higher pressuremicrowave heating zone, while the second pressure adjustment zone 114 bmay transition the carrier from a higher pressure holding zone 120 (or ahigher-pressure portion of the quench zone) to a lower pressure quenchzone 122, or portion thereof.

After thermalization, the loaded carrier may be introduced into themicrowave heating zone 116, wherein the articles may be heated using aportion of the microwave energy discharged into a microwave heatingchamber via one or more microwave launchers. Various configurations ofmicrowave heating systems of the present invention may employ microwaveenergy having a frequency within one or more of the above ranges, with afrequency of about 915 MHz being preferred. Further, as discussed above,the microwave energy discharged into the microwave heating chamber maybe polarized. In addition to microwave energy, the microwave heatingzone may optionally utilize one or more other types of heat sources suchas, for example, various conductive or convective heating methods ofdevices. However, it is generally preferred that at least about 50, atleast about 55, at least about 60, at least about 65, at least about 70,at least about 75, at least about 80, at least about 85, at least about90, or at least about 95 percent of the energy used to heat the articlescan be microwave energy from a microwave source.

One example of a microwave heating zone 316 suitable for use in theinventive system is schematically illustrated in FIG. 15. The microwaveheating zone 316 shown in FIG. 15 generally includes a microwave heatingchamber 330, at least one microwave generator 332 for generatingmicrowave energy, and a microwave distribution system 334 for directingat least a portion of the microwave energy from the generator orgenerators 332 to the microwave heating chamber 330. The system furthercomprises one or more microwave launchers 322 for discharging microwaveenergy into the interior of the microwave heating chamber 330. Themicrowave heating zone 316 may also include a convey system 340 having aconvey line with a support for transport a plurality of carriers loadedwith groups of articles through the microwave heating zone.

Each microwave launcher 322 may be configured to emit a particularamount of microwave energy into the microwave heating chamber 330. Forexample, each microwave launcher 322 may be configured to emit at leastabout 5, at least about 7, at least about 10, at least about 15 kWand/or not more than about 50, not more than about 40, not more thanabout 30, not more than about 25, not more than about 20, or not morethan about 17 kW. When the system includes two or more microwavelaunchers, each launcher 322 may emit the same amount of energy as oneor more other launchers, or at least one launcher may emit a different(e.g., lower or higher) amount of energy, as compared to at least one ofthe other launchers. Overall, the total amount of energy discharged intothe microwave heating chamber 330 can be at least about 25 kW, at leastabout 30 kW, at least about 35 kW, at least about 40 kW, at least about45 kW, at least about 50 kW, at least about 55 kW, at least about 60 kW,at least about 65 kW, at least about 70 kW, or at least about 75 kWand/or not more than about 100 kW, not more than about 95 kW, not morethan about 90 kW, not more than about 85 kW, not more than about 80 kW,not more than about 75 kW, not more than about 70 kW, or not more thanabout 65 kW.

When the system includes two or more microwave launchers 322, at leastsome of the launchers, shown as groups 322 a and 322 b in FIG. 15, maybe positioned on the same side of the microwave heating chamber 330.These same-side launchers 322 a or 322 b may be axially spaced from oneanother along the length of the microwave heating chamber, in adirection parallel to the direction of travel of the carrier 310 passingthrough the chamber. The microwave system may also include two or moresame-side launchers that are laterally spaced from one another in adirection generally perpendicular to the direction of travel of thecarriers through the chamber. Additionally, or in the alternative, themicrowave heating system may also include at least two launcherspositioned on opposite sides of the microwave chamber. These opposed oroppositely disposed launchers, such as those in groups 322 a and 322 bshown in FIG. 15, may be oppositely facing, such that launch openings ofthe launchers are substantially aligned, or staggered such that thelaunch openings of opposed launchers are axially and/or laterally spacedfrom each other.

Each of the microwave launchers utilized in the microwave heating zonemay be of any suitable configuration. Several exemplary microwavelaunchers are described with respect to FIGS. 16, 17, and 18 a-c.Turning first to FIG. 16, one example of a microwave launcher 822comprises a set of broader opposing sidewalls 832 a,b and a set ofnarrower opposing end walls 834 a,b, which collectively define asubstantially rectangular launch opening 838. The launch opening 838 canhave a width (W₁) and a depth (D₁) that are defined by the lowerterminal edges of sidewalls 832 a,b and 834 a,b, respectively. The depth(D₁) of launch opening 838 is less than its width (W₁) and is typicallyoriented in a direction perpendicular to the direction of travel of thecarriers moving through the microwave heating chamber. In other words,launch opening 838 may be elongated in the direction of travel of thecarriers (or the direction of extension of the microwave chamber), sothat the width of the launcher defined by the longer terminal edges ofthe sidewalls 832 a,b are oriented parallel to the direction of travel(or the direction of extension), while the depth of the launcher definedby the shorter terminal edges of the end walls 834 a,b are alignedsubstantially perpendicular to the direction of travel (or extension).

Views of one of sidewalls 832 and several examples of suitable end walls834 are shown in FIGS. 17 and 18 a-c, respectively. Optionally, at leastone of the pair of sidewalls 832 a,b and the pair of end walls 834 a,bcan be flared such that the inlet dimension (width W₀ or depth D₀) issmaller than the outlet dimension (width W₁ or depth D₁), asrespectively illustrated in FIGS. 17 and 18 a. If flared, the sideand/or end walls define respective width and depth flare angles, θ_(w)and θ_(d), as shown in FIGS. 17 and 18 a. The width and/or depth flareangles θ_(w) and/or θ_(d) can be at least about 2°, at least about 5°,at least about 10°, or at least about 15° and/or not more than about45°, not more than about 30°, or not more than about 15°. When present,the values for the width and depth flare angles θ_(w) and θ_(d) can bethe same, or each of θ_(w) and θ_(d) may have a different value. In somecases, the end walls 838 a,b of the microwave launcher 822 may have adepth flare angle θ_(d) that is smaller than the width flare angleθ_(w). For example, the depth flare angle θ_(d) can be not more thanabout 0°, such that the inlet depth D₀ and the outlet dimension D₁ ofmicrowave launcher 822 are substantially the same, as shown in FIG. 18b, or the depth flare angle θ_(d) may be less than 0°, such that D₁ issmaller than D₀, as shown in FIG. 18c . Other examples of suitablemicrowave launchers are described in detail in the '516 Application.

In some embodiments, the launch opening or openings defined by one ormore microwave launchers used in the present invention may be at leastpartially covered by a substantially microwave-transparent window forfluidly isolating the microwave heating chamber from the microwavelauncher. The microwave transparent windows, when present, may preventfluid flow between microwave chamber and the microwave launchers, whilestill permitting a substantial portion of the microwave energy from thelaunchers to pass therethrough and into the microwave chamber. Thewindows may be formed of any suitable material, including, but notlimited to, one or more thermoplastic or glass material such asglass-filled Teflon, polytetrafluoroethylene (PTFE), poly(methylmethacrylate (PMMA), polyetherimide (PEI), aluminum oxide, glass, andcombinations thereof. The average thickness of each window may be atleast about 4 mm, at least about 6 mm, at least about 8 mm, or at leastabout 10 mm and/or not more than about 20 mm, not more than about 16 mm,or not more than about 12 mm. Each window may be able to withstand apressure difference of at least about 40 psig, at least about 50 psig,at least about 75 psi and/or not more than about 200 psig, not more thanabout 150 psig, or not more than about 120 psi without breaking,cracking, or otherwise failing.

Turning back to FIG. 15, as the carrier 310 passes through the microwaveheating zone 330, the articles may be heated so that the coldest portionof the articles achieves a target temperature. When the microwaveheating system is a sterilization or pasteurization system, the targettemperature achieved by the articles can be a sterilization orpasteurization target temperature of at least about 65° C., at leastabout 70° C., at least about 75° C., at least about 80° C., at leastabout 85° C., at least about 90° C., at least about 95° C., at leastabout 100° C., at least about 105° C., at least about 110° C., at leastabout 115° C., at least about 120° C., at least about 121° C., at leastabout 122° C. and/or not more than about 130° C., not more than about128° C., or not more than about 126° C. Unless otherwise indicated, thetemperature of an article refers to the temperature measured at thecoldest portion of that article.

The microwave heating chamber 330 may be at least partially liquidfilled and at least a portion, or all, of the articles in the carriermay be submerged in the liquid medium during heating. The average bulktemperature of the liquid in the microwave heating chamber 330 may varyand, in some cases, can depend on the amount of microwave energydischarged into the microwave heating chamber. The average bulktemperature of the liquid in the microwave heating chamber 330 can be atleast about 70° C., at least about 75° C., at least about 80° C., atleast about 85° C., at least about 90° C., at least about 95° C., atleast about 100° C., at least about 105° C., at least about 110° C., atleast about 115° C., or at least about 120° C. and/or not more thanabout 135° C., not more than about 132° C., not more than about 130° C.,not more than about 127° C., or not more than about 125° C.

As the carrier 310 passes through the microwave heating chamber 330, thearticles may be heated to the target temperature in a relatively shortperiod of time, which can help minimize any damage or degradation of thearticles. For example, the average residence time of each articlepassing through the microwave heating zone 316 can be at least about 5seconds, at least about 20 seconds, at least about 60 seconds and/or notmore than about 10 minutes, not more than about 8 minutes, not more thanabout 5 minutes, not more than about 3 minutes, not more than about 2minutes, or not more than about 1 minute. The minimum temperature of thearticles heated in the microwave heating zone 316 can increase by atleast about 5° C., at least about 10° C., at least about 15° C., atleast about 20° C., at least about 30° C., at least about 40° C., atleast about 50° C., at least about 75° C. and/or not more than about150° C., not more than about 125° C., or not more than about 100° C.

In some embodiments, the microwave heating chamber 330 can be operatedat approximately ambient pressure. Alternatively, it may be apressurized microwave chamber 330 that operates at a pressure that is atleast 5 psig, at least about 10 psig, at least about 15 psig, or atleast about 17 psig and/or not more than about 80 psig, not more thanabout 60 psig, not more than about 50 psig, or not more than about 40psig above ambient pressure. As used herein, the term “ambient” pressurerefers to the pressure exerted by the fluid in the microwave heatingchamber without the influence of external pressurization devices.

Referring again to FIGS. 14a and 14b , upon exiting the microwaveheating zone 116, the loaded carrier may be passed to an optionalholding zone 120, wherein the temperature of the articles can bemaintained at or above a certain target temperature for a predeterminedperiod of time. For example, in the holding zone 120, the temperature ofthe coldest part of the article can be held at a temperature at or abovea predetermined minimum temperature of at least about 70° C., at leastabout 75° C., at least about 80° C., at least about 85° C., at leastabout 90° C., at least about 95° C., at least about 100° C., at leastabout 105° C., at least about 110° C., at least about 115° C., or atleast about 120° C., at least about 121° C., at least about 122° C.and/or not more than about 130° C., not more than about 128° C., or notmore than about 126° C., for a period of time (or “hold period”) of atleast about 1 minute, at least about 2 minutes, or at least about 4minutes and/or not more than about 20 minutes, not more than about 16minutes, or not more than about 10 minutes.

Thereafter, the heated articles, which may be sufficient pasteurized orsterilized, exit the holding zone 120, may be introduced into a quenchzone 122, wherein the articles are cooled as rapidly as possible viasubmersion in a cooled fluid. The quench zone 122 may reduce theexternal surface temperature of the articles by at least about 30° C.,at least about 40° C., at least about 50° C. and/or not more than about100° C., not more than about 75° C., or not more than about 50° C. in atime period of at least about 1 minute, at least about 2 minutes, atleast about 3 minutes and/or not more than about 10 minutes, not morethan about 8 minutes, or not more than about 6 minutes. Any suitablefluid may be used in the quench zone 122 and, in some cases, the fluidmay include a liquid similar to, or different than, the liquid used inthe microwave heating zone 116 and/or the holding zone 120. When removedfrom the quench zone 122, the cooled articles can have a temperature ofat least about 20° C., at least about 25° C., at least about 30° C.and/or not more than about 70° C., not more than about 60° C., or notmore than about 50° C. Once removed from quench zone 122, the cooled,treated articles can then be removed from microwave heating zone 100 forsubsequent storage or use.

Microwave heating systems of the present invention can becommercial-scale heating systems capable of processing a large volume ofarticles in a relatively short time. In contrast to conventional retortsand other small-scale systems that utilize microwave energy to heat aplurality of articles, microwave heating systems as described herein canbe configured to achieve an overall production rate of at least about 5packages per minute, at least about 10 packages per minute, at leastabout 15 packages per minute per convey line, at least about 20 packagesper minute per convey line, at least about 25 packages per minute perconvey line, or at least about 30 packages per minute per convey line,measured as described in the '516 Application.

Articles processed in a microwave pasteurization or sterilization systemas described above may subsequently be obtained by a consumer, who mayreheat the articles prior to consumption. As discussed above, thereheating step may include heating one or more articles in asmaller-scale consumer-type microwave oven. Depending on the size of theoven, the total number of articles heated at once can be not more than5, not more than 4, not more than 3, or 2 or less. Typically, themicrowave energy discharged by a consumer microwave oven isnon-polarized or randomly polarized and has a frequency of about 2450MHz. Additionally, articles re-heated in a consumer microwave oven arenot secured in a carrier, as is done in a larger-scale pasteurization orsterilization system described previously.

The articles reheated in a consumer microwave oven may be heated for aperiod of at least about 15 seconds, at least about 20 seconds, at leastabout 25 seconds, at least about 30 seconds, at least about 45 seconds,at least about 1 minute, at least about 1.5 minutes, at least about 2minutes, at least about 2.5 minutes, or at least about 3 minutes and/ornot more than about 10 minutes, not more than about 8 minutes, not morethan about 7 minutes, not more than about 6.5 minutes, not more thanabout 6 minutes, not more than about 5.5 minutes, not more than about 5minutes, not more than about 4.5 minutes, not more than about 4 minutes,not more than about 3.5 minutes, or not more than about 3 minutes.Typically, consumer microwave ovens are operated at atmospheric pressureand do not include liquid-filled chambers.

The temperature achieved by the hottest portion of the foodstuff beingreheated can be at least about 35, at least about 40, at least about 45,at least about 50, at least about 55, at least about 60, at least about65, at least about 70, at least about 75, or at least about 80° C.and/or not more than about 100, not more than about 95, not more thanabout 90, not more than about 85, not more than about 80, not more thanabout 75, not more than about 70, not more than about 65, not more thanabout 60, not more than about 55, not more than about 50, not more thanabout 45, or not more than about 40° C. The temperature achieved by thecoldest portion of the foodstuff being reheated can be at least about22, at least about 25, at least about 27, at least about 30, at leastabout 32, at least about 35, at least about 37, at least about 40, atleast about 42, at least about 45, at least about 47, at least about 50,at least about 52, at least about 55, at least about 57, or at leastabout 60° C. and/or not more than about 95, not more than about 90, notmore than about 85, not more than about 80, not more than about 75, notmore than about 70, not more than about 65, not more than about 60, notmore than about 55, or not more than about 50° C.

According to the present invention, methods of designing a package for aparticular foodstuff or other item to be heated in commercial microwavepasteurization/sterilization systems and at-home consumer microwaveovens as described herein are also provided. The major steps of onemethod 600 are shown in the flow chart provided in FIG. 18.

As shown in FIG. 18, the first step of method 600 for designing apackage including one or more energy control elements is to fill aninitial package with a test material to form a test article, as shown byblock 610. The initial package may be a commercially-available package,or it may be custom-made, and it may or may not already include one ormore microwave energy control elements. In some cases, the initialpackage used in this method may be a modified package that resulted froma previous trial.

Any suitable test material may be used and can include, for example, asample of the exact foodstuff or other item which will ultimately beused to fill the package, or a substitute material used to simulate thefoodstuff or other item. One example of a suitable substitute testmaterial is whey gel pudding, such as that commercially available fromAmeriqual Group, LLC (Evansville, Ind., USA). The initial package may befilled in any suitable manner. Generally, the initial package may beformed of conventional materials and may not include any type of energycontrol element, although situations where the initial package includesan energy control element are not excluded.

Once the initial package is filled, it may be heated in a microwaveheating system using microwave energy, as shown by block 612 a in FIG.18. The microwave heating system may be a large- or pilot-scaleliquid-filled microwave heating system that utilizes polarized microwaveenergy, as described above with respect to FIGS. 14a and 14b , or it maybe a lab-scale system designed to simulate the behavior of alarger-scale system. Alternatively, the test article may be heated in aconsumer-type microwave oven that utilizes non-polarized or randomlypolarized microwave energy.

During at least a portion of the heating step, the temperature of thetest material may be measured in one or more, preferably two or more,locations, as shown by block 612 b in FIG. 18. Such temperaturemeasurement may be performed using any suitable instrument and, in somecases, may be performed using temperature probes positioned within thetest material and sealed into the packages. In these cases, thetemperature probe or probes would be placed into the packages along withthe test material during the filling step, shown as block 610 in FIG.18. Alternatively, other types of temperature measurement devices may beused that may be positioned near or within the article after it has beenfilled.

After the article has been heated to a target temperature, it may beremoved from the microwave heating zone and cooled. As shown by block614 in FIG. 18, from the temperature measurements taken during theheating step, the location of at least one hot or cold spot within thepackage may be determined. In some cases, such a determination may beperformed using temperature data obtained during the heating, as well ascommercially available modeling software. In some cases, the location ofthe hot or cold spot may depend on the position of the article within acarrier, while, in other cases, it may not. The article may exhibit atleast one hot spot, at least one cold spot, or at least one hot spot andat least one cold spot.

As shown by block 616, the method 600 of designing a modified packagefurther includes the step of creating a modified package including atleast one energy control element by taking one or more of the followingactions: (i) adding a microwave inhibiting element near a hot spot; (ii)adding a microwave enhancing element near a cold spot; (iii) removing amicrowave inhibiting element from near a cold spot; and (iv) removing amicrowave enhancing element from a hot spot. In some cases, two or more,three or more, or even all four actions may be taken to form a modifiedpackage. As discussed previously, the microwave control element may be aselective microwave control element and may inhibit or enhance one typeof microwave energy more than another.

Thereafter, as shown by block 618 in FIG. 18, the modified package maybe filled with the same test material used to fill the initial packageand form the test article. As shown by block 620, the resulting modifiedarticle may again be heated in the same microwave heating system as thetest article, and the same system may be used to measure the temperatureof the test material during the heating. In some cases, the temperatureof the hot and/or cold spots previously determined may be measured and,after the heating step, the temperature measurements of the modifiedarticle may be compared with those taken during heating of the testarticle. Preferably, the temperatures of the hot and/or cold spot islower and/or higher, respectively, so that the variation between thetemperature of the hot and/or cold spot and the rest of the material isless than it was during heating of the test article. If the temperaturesof the hot and/or cold spots are subsequently higher and/or lower thanthose measured during heating of the test article, the package may againbe modified to include one or more energy control elements. Each of thesteps 612 through 620 of method 600 may be repeated as many times asnecessary to provide a final modified package which minimizes thepresence of hot and cold spots and ensures more uniform heating of thematerial within the package.

Definitions

As used herein, the terms “comprising,” “comprises,” and “comprise” areopen-ended transition terms used to transition from a subject recitedbefore the term to one or more elements recited after the term, wherethe element or elements listed after the transition term are notnecessarily the only elements that make up the subject.

As used herein, the terms “including,” “includes,” and “include” havethe same open-ended meaning as “comprising,” “comprises,” and“comprise.”

As used herein, the terms “having,” “has,” and “have” have the sameopen-ended meaning as “comprising,” “comprises,” and “comprise.”

As used herein, the terms “containing,” “contains,” and “contain” havethe same open-ended meaning as “comprising,” “comprises,” and“comprise.”

As used herein, the terms “a,” “an,” “the,” and “said” mean one or more.

As used herein, the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itselfor any combination of two or more of the listed items can be employed.For example, if a composition is described as containing components A,B, and/or C, the composition can contain A alone; B alone; C alone; Aand B in combination; A and C in combination; B and C in combination; orA, B, and C in combination.

The preferred forms of the invention described above are to be used asillustration only, and should not be used in a limiting sense tointerpret the scope of the present invention. Obvious modifications tothe exemplary one embodiment, set forth above, could be readily made bythose skilled in the art without departing from the spirit of thepresent invention.

The inventors hereby state their intent to rely on the Doctrine ofEquivalents to determine and assess the reasonably fair scope of thepresent invention as pertains to any apparatus not materially departingfrom but outside the literal scope of the invention as set forth in thefollowing claims.

What is claimed is:
 1. A process for microwave heating articles, theprocess comprising: heating an article using microwave energy dischargedinto a microwave heating chamber, wherein the article includes a packagehaving an energy control element, and wherein the energy control elementis positioned such that, during heating using the microwave energy,contents of the article are at least one of heated to a substantiallydifferent temperature or heated at a substantially different heatingrate than if the energy control element was not present.
 2. The processof claim 1, wherein: the contents are heated at a substantiallydifferent heating rate, and the substantially different heating ratewith the energy control element is at least 2° C./min different thanwithout the energy control element.
 3. The process of claim 1, wherein:the contents are heated to a substantially different temperature, andthe substantially different temperature with the energy control elementis at least 5° C. different than the temperature without the energycontrol element.
 4. The process of claim 1, wherein the energy controlelement comprises a susceptor.
 5. The process of claim 1, wherein theenergy control element comprises a susceptor and wherein a heating rateof the contents is at least 10° C./min.
 6. The process of claim 1,wherein the energy control element comprises a susceptor and wherein thecontents are heated to at least 100° C.
 7. The process of claim 1,wherein the energy control element includes a microwave inhibitingelement and the contents are at least one of heated to a lowertemperature or at a slower heating rate than if the microwave inhibitingelement was not present.
 8. The process of claim 1, wherein the energycontrol element comprises a microwave inhibiting element and thecontents are heated at less than about 20° C./min.
 9. The process ofclaim 1, wherein the energy control element comprises a microwaveinhibiting element and the contents are heated to less than about 125°C.
 10. The process of claim 1, wherein the energy control elementcomprises a plurality of energy control strips located on a surface ofthe package.
 11. The process of claim 1, wherein the energy controlelement comprises a plurality of energy control strips located on asurface of the package, wherein the energy control strips have a widthfrom and including about 1/16 inch to and including about ⅛ inch. 12.The process of claim 1, wherein the energy control element comprises afirst energy control strip and a second energy control strip spacedapart from the first energy control strip to define an open area, andwherein the open area has a width that is at least 25 percent greaterthan an average width of the first energy control strip and the secondenergy control strip.
 13. The process of claim 1, wherein the contentsinclude one or more foodstuffs.
 14. The process of claim 1, wherein themicrowave energy is polarized.
 15. The process of claim 1, wherein themicrowave energy has a frequency from and including about 850 MHz to andincluding about 1050 MHz.
 16. The process of claim 1, wherein themicrowave heating chamber is at least partially filled with a liquidmedium and the article is at least partially submerged in the liquidmedium during heating.
 17. A process for heating using microwave energy,the process comprising: subsequent to heating an article using firstmicrowave energy to sterilize or pasteurize contents of the article,reheating the article with second microwave energy to reheat thecontents, wherein the first microwave energy and the second microwaveenergy differ in at least one of polarization, frequency, and intensity,wherein the article includes a package having an energy control element,and wherein the energy control element is positioned such that, duringat least one of heating with the first microwave energy and reheatingwith the second microwave energy, contents of the article are at leastone of heated to a substantially different temperature or heated at asubstantially different heating rate than if the energy control elementwas not present.
 18. The process of claim 17, wherein the firstmicrowave energy is polarized microwave energy and the second type ofmicrowave energy is one of non-polarized or randomly polarized microwaveenergy.
 19. The process of claim 17, wherein the first type of microwaveenergy has a frequency of not more than about 1200 MHz and the secondtype of microwave energy has a frequency of at least about 2200 MHz. 20.The process of claim 17, wherein the control element is configured toreflect the first microwave energy and to be transparent to the secondmicrowave energy.